The long range goal is to test my hypothesis that "Calcium modulated proteins contain EF hands". The specific research goal over the next five years is to determine the crystal structures of several proteins that might reasonably be expected to contain the EF hand conformation. We have been unable to crystallize these proteins but we are continuing and intensifying our efforts to purify, characterize, and crystallize: brain phosphodiesterase activator protein (PAP), tubulin, S-100 troponin and the calcium binding protein from wheat flour. In addition other laboratories have sent us samples for attempted crystallization of troponin, tubulin, PAP, S-100, L-1 from squid axon and an unnamed calcium binding protein from crayfish muscle. BIBLIOGRAPHIC REFERENCES: Kretsinger, R.H. "Hypothesis: Calcium Modulated Proteins Contain EF Hands" in Calcium Transport in Contraction and Secretion (1975) eds. E. Carafoli, W. Drabikowski and A. Margreth. North-Holland Publishing Co., Amsterdam pp. 469-478. Kretsinger, R.H. and Nelson, D.J. "Calcium in Biological Systems" Coordination Chemistry Reviews. (1976) 18: 29-124.